By name: concrete-column-design description: "This skill should be used when an architect or structural designer needs to verify PDF-backed concrete column requirements such as longitudinal reinforcement ratio, minimum longitudinal-bar count, minimum shear reinforcement, and column splice rules in Taiwan's concrete structure design code." user-invocable: true license: CC-BY-SA-4.0 compatibility: claude-code,opencode,agent-skills metadata: audience: architects region: taiwan class: C regulation: 建築物混凝土結構設計規範
Concrete Column Design
Overview
Design requirements for reinforced concrete columns in Taiwan, limited here to items directly verified against the uploaded PDF: longitudinal reinforcement ratio, minimum longitudinal-bar count, minimum shear reinforcement, and column splice rules. Seismic confinement details that were not fully transcribed remain chapter references only. For cover and splice fundamentals, see concrete-general-requirements.
Section 1: Column Classification
1.1 By Cross-Section Shape
| Type | Section | Reinforcement Type |
|---|---|---|
| Rectangular column (矩形柱) | Square or rectangle | Ties (繫筋) |
| Circular column (圓柱) | Circle | Spirals (螺旋筋) or circular ties |
| L-shaped / irregular | Composite shapes | Combined tie arrangement |
1.2 By Primary Loading
| Type | Characteristics | Design Consideration |
|---|---|---|
| Axially loaded | Gravity load dominant | ρg within limits; tie spacing |
| Eccentrically loaded | Combined axial + bending | Interaction diagram (P-M curve) |
| Short column | Slenderness ratio < limit | Direct strength calculation |
| Slender column | Slenderness ratio ≥ limit | Moment magnification required |
Section 2: Main Bar Requirements (主筋)
2.1 Gross Reinforcement Ratio (ρg)
$$\rho_g = \frac{A_{st}}{A_g}$$
Where:
- Ast = total area of longitudinal steel
- Ag = gross cross-sectional area of column
| Limit | Value | Reason |
|---|---|---|
| Minimum | 1.0% (0.01) | Below this, column cannot resist minimum bending; creep becomes excessive |
| Maximum | 8.0% (0.08) | Above this, bar congestion at splices and joints prevents proper concrete casting |
| Practical note from commentary | Reinforcement ratio is generally not preferred above 4% when all lap splices occur at one location | Constructability warning only |
Design Check: ρg < 1% → ERROR. ρg > 8% → ERROR.
Source: 10.6.1.1 and its commentary.
2.2 Minimum Number of Main Bars
| Column Shape | Minimum Bars |
|---|---|
| Rectangular ties | 4 bars (one at each corner) |
| Circular spirals | 6 bars |
| Triangular ties | 3 bars |
Source: 10.7.3.1.
2.3 Source-Control Note
Bar-size limits, bundling, and development-length effects must be resolved from Chapter 25 when needed. This skill does not preserve unverified bar-size assumptions.
Section 3: Transverse Reinforcement Clauses
The following clauses were verified in the PDF and should be used instead of inferred detailing rules:
| Topic | Governing Clause |
|---|---|
| Minimum shear reinforcement trigger | 10.6.2.1 |
| Minimum shear reinforcement formula | 10.6.2.2 |
| Minimum bar spacing reference | 10.7.2.1 → Chapter 25.2 |
| Minimum longitudinal-bar count | 10.7.3.1 |
| Tie / spiral / closed-tie detailing | 10.7.6.1.2 → Chapter 25.7 |
Do not infer tie-spacing rules beyond what has been directly transcribed from the PDF.
Section 4: Minimum Shear Reinforcement
When shear reinforcement is required, the PDF gives:
$$A_{v,min} = \max\left(0.062\frac{\sqrt{f'c}}{f{yt}}b_ws,\ 0.35\frac{b_ws}{f_{yt}}\right)$$
This reflects clause 10.6.2.2.
Source: 10.6.2.2.
Section 5: Column Splice Rules Verified from the PDF
5.1 Compression Lap Splices
If column bars are in compression, compression lap splices may be used. Clause 10.7.5.2.1 allows reduction of lap length, but not below 30 cm:
- tied columns: multiply by 0.83 when the tie confinement requirement inside the splice zone is met
- spiral columns: multiply by 0.75 when the spiral confinement requirement inside the splice zone is met
5.2 Tension Lap Splices
Clause 10.7.5.2.2 gives the verified classification:
| Bar Stress Under Factored Load | Detail Condition | Splice Type |
|---|---|---|
| ≤ 0.5fy | at any section, spliced bars ≤ 50% and splice locations staggered by at least ψgld | Class A |
| ≤ 0.5fy | all other cases | Class B |
| > 0.5fy | all cases | Class B |
Source: 10.7.5.2.2, Table 10.7.5.2.2.
5.3 Seismic Restrictions
Special seismic column confinement and splice-location restrictions must be checked directly against Chapter 18. This skill does not restate unverified hinge-zone dimensions.
Section 6: Placement and Support Details Verified from the PDF
- bottom tie or closed tie in a story must be placed no farther than one-half tie spacing above the footing or slab top: 10.7.6.2.1
- top tie or closed tie in a story must be placed no farther than one-half tie spacing below the lowest horizontal reinforcement of the slab / capital / drop panel; with beams or brackets on all four sides, not farther than 7.5 cm below the lowest beam or bracket reinforcement: 10.7.6.2.2
- if anchors or precast connectors are placed at a column end, transverse reinforcement must be provided within 12.5 cm of the end: 10.7.6.1.5, 10.7.6.1.6
Section 7: AI Design Check Table — Column
| Check | Condition | AI Action |
|---|---|---|
| ρg minimum | ρg < 1% | ERROR: Insufficient longitudinal reinforcement. Column cannot resist minimum moment. |
| ρg maximum | ρg > 8% | ERROR: Excessive reinforcement — casting impossible at splices. |
| Compression splice reduction | 0.83 or 0.75 reduction applied without clause 10.7.5.2.1 confinement condition | ERROR: Splice reduction not justified. |
| Tension splice class | Class A used when stress/detail condition in 10.7.5.2.2 is not met | ERROR: Upgrade to Class B. |
| Seismic splice location | Column is part of seismic system and Chapter 18 location check not performed | WARNING: Verify Chapter 18 splice restrictions before approval. |
| Min bars (rectangular) | < 4 main bars | ERROR: Minimum 4 bars required for rectangular tied column. |
Section 8: MCP Tool Examples
# Search for column reinforcement ratio requirements
taiwan-building-code_search_building_code(query="柱 縱向鋼筋比 ρg 最小 最大", limit=10)
# Search for tie spacing requirements
taiwan-building-code_search_building_code(query="柱 繫筋間距 橫向鋼筋", limit=10)
# Search for seismic column requirements
taiwan-building-code_search_building_code(query="柱 耐震 特殊圍束筋 塑鉸區 lo", limit=10)
# Search for splice location in columns
taiwan-building-code_search_building_code(query="柱 搭接位置 塑鉸區 禁止", limit=10)
# Official interpretations
taiwan-building-code_search_building_interpretations(query="柱 繫筋 圍束 計算方式")
Additional Resources
- General requirements (cover, development length): concrete-general-requirements
- Beam design: concrete-beam-design